1. Technical Field
The present disclosure relates generally to circulatory support systems, and, more particularly, to a circulatory support system to provide partial or total bypass of the heart. The present disclosure is further directed to an axial flow pump and a portable microprocessor-based controller each being adapted for use in the circulatory support system.
2. Background of the Related Art
Mechanical blood pumps are commonly utilized to temporarily support or substitute the pumping function of the heart during heart surgery or during periods of heart failure. The most widely applied blood pumps include roller pumps and centrifugal pumps. Typically, these pumps are a component of a cardiopulmonary bypass system (e.g., a heart-lung machine) which includes an oxygenator, a heat exchanger, blood reservoirs and filters, and tubing which transports the blood from the patient through the bypass system and back to the patient. With these systems, blood is withdrawn from the patient via uptake cannula positioned within the vena cavae and atria or ventricles of the heart and pumped back into the pulmonary artery and aorta via a return cannula.
Although the aforedescribed cardiopulmonary bypass systems have been generally effective for their intended purposes, these systems are subject to certain disadvantages which detract from their usefulness. In particular, conventional bypass systems are relatively complicated and expensive to manufacture, expose the blood to a high surface area of foreign materials which may damage the blood, require full anticoagulation and cooling of the heart, and require considerable set up time and continual management by a skilled technician. These systems also require mechanical oxygenation of the blood which can have adverse affects on the patient.
U.S. Pat. No. 4,610,656 to Mortensen/Mehealus Partnership discloses a semi-automatic heart-lung substitution system. The Mortensen '656 system includes a roller pump which pumps blood from the patient's right heart via a venous cannula to a membrane oxygenator connected at the output of the roller pump. From the oxygenator, the blood flows to a compliance reservoir which is connected to a pulsatile left heart pump. Blood is pumped by the pulsatile left heart pump through a filter and bubble trap and then returned to the patient's arterial system through an arterial cannula. The Mortensen '656 system, however, is also a relatively complex device including several pumps and an oxygenator and, consequently, requires attendance of skilled technicians for set-up and operation.